Evaluating MMPs for a big app. What should we ask before signing?

Start with the bill at your real volume, not the headline rate. Per-conversion and per-install pricing diverge fast, and units differ: some vendors count conversions, which can include re-engagements, while others bill attributed installs only. Then go line by line through the plan you would actually buy. Ask whether deferred deep linking ships in the same SDK, since two SDKs means two datasets to reconcile. Get SKAN and AdAttributionKit support in writing. Ask which modules are paid add-ons, because at some vendors deep linking, fraud prevention or real-time impression-level ad revenue sit on higher tiers or cost extra. Ask who answers support tickets in your time zone. Finally, list what you need beyond attribution, such as incrementality testing, media mix modelling or clean rooms, and ask each vendor what it includes. A fuller checklist: https://linkrunner.io/mmp-evaluation-checklist